Spray a 9x13 baking dish with non stick spray. Sprinkle bread evenly over the bottom, sprinkle blueberries over bread.
In a large bowl, beat eggs. Add milk, sugar, vanilla and cinnamon. Whisk until all ingredients are combined
Pour egg mixture over the bread. Dot with butter
Cover and refrigerate at least one hour. You can prepare this the night before and refrigerate overnight.
When ready to bake, preheat oven to 375. Bake for 35-40 minutes.